WASHINGTON: US President Donald Trump on Friday lashed out at the FBI inquiry into possible collusion between Moscow and his campaign, and refused to rule out pardoning former aide Michael Flynn, who pleaded guilty to lying about his contacts with Russia.

Trump said it was too early to discuss any pardon for his ex-national security advisor -- which would prompt a political firestorm.

So far, the FBI’s sprawling probe into Russia’s meddling in the 2016 election has ensnared at least four members of his campaign inner circle.

“I don’t want to talk about pardons for Michael Flynn yet,” Trump said before leaving the White House to give remarks at a graduation ceremony at the Federal Bureau of Investigation’s academy in Quantico, Virginia.

“I can say this -- when you look at what’s gone on with the FBI and with the Justice Department, people are very, very angry,” he said.

“When everybody -- not me, when everybody -- the level of anger at what they’ve been witnessing with respect to the FBI is certainly very sad.”

US intelligence agencies have concluded that Russian President Vladimir Putin ordered his intelligence and cyber services to help turn the election in Trump’s favour.

“There is absolutely no collusion. I didn’t make a phone call to Russia. I have nothing to do with Russia. Everybody knows it. That was a Democrat hoax. It was an excuse for losing the election,” he said.

Trump also blasted as “disgraceful” recently released text messages exchanged by an FBI agent and a lawyer involved in the probe who were critical of the president.

The agent, Peter Strzok, has been removed from the investigation being led by special counsel Robert Mueller, a former FBI director.

Separately, Trump called on fellow Republican Roy Moore on Friday to concede to Democrat Doug Jones in the Alabama US Senate race, following the party’s stinging loss in the southern US state earlier this week.

Moore, whose controversial candidacy was beset by allegations that he sexually assaulted or pursued teenage girls while in his 30s, has so far refused to admit defeat in Tuesday’s election that saw Jones win by 1.5 percentage points with 99 per cent of the ballots counted.

The embattled Republican has made two statements since his loss, but has not conceded even as Trump and others have reached out to congratulate Jones, a former prosecutor, on his win.

“I would certainly say he should,” Trump, who endorsed Moore in the final stage of the campaign, told reporters at the White House.

“He tried,” Trump added, referring to Moore’s campaign efforts and reiterating his earlier comments that as the party’s top leader he would have liked to keep the seat in Republican hands.

Jones defeated the former judge in a special election to replace Jeff Sessions, who left the Senate to serve as US Attorney General under Trump. State officials have said the outcome is unlikely to change even as provisional ballots are counted.

The Democratic win would narrow Republicans’ hold on the Senate to 51 out of 100 seats. It has also buoyed Democrats’ hopes of a potential comeback for the party in the 2018 midterm elections.